The goal of this proposal is to make a complete contig of mouse Chromosome 16 as YAC clones and to develop and sequence markers to provide an STS every 100 kb along the chromosome. The YACs will be developed so as to assure that these clones represent a long term resource for biological analysis as well as a transiently-useful mapping reagent. YACs will be developed from a mouse X human somatic cell hybrid, assuring a low chimera frequency (ca. 10%) and providing a useful human genomic YAC library as a by-product. YAC mapping and especially STS placement will be facilitated by the use of state of the art YAC vectors, yeast strains and methodologies that enlist yeast systems for genetic analysis as a "silent partner" in the effort. In the first stage of this grant, a high resolution backcross panel consisting of 335 crossover points on Chr16 was developed. This map will permit efficient assignment, position and orientation of YACs and nascent contigs. The approach will take full advantage of the effort to generate 10,000 markers in the Genome Center at MIT, which will provide ca. 400 markers of Chr16 over the course of the project. Two hundred additional markers will be utilized. Up to 100 of these will derive from efforts of others to identify genes in evolutionarily conserved portions of human chromosomes. Within the project, several strategies will be used to analyze complex markers representing dozens of sequences on Chr16; markers from early embryonic stage-specific cDNA libraries representing genes that are inaccessible in human beings; random marker strategies; and markers from YACs of known positions in the CEPH/Genethon human chromosome 21 contig (and others as they become available). The final recombinational and physical maps will meet or exceed the five year goals for the mouse genome, will establish the most detailed comparative maps constructed to date, will provide considerable information about the positions of genes, and will derive a set of YACs as useful as any made to date for anticipated and unanticipated advances in genome analysis. This will be accomplished in a cost-competitive manner.